Apparatus for continuously casting and refining a metal in a bottomless mold



June 30, 1970 BABEL APPARATUS FOR CONTINUOUSLY CASTING AND REFINING AMETAL IN A BOTTOMLESS MOLD Filed Dec. 27, 1967 United States PatentAPPARATUS FOR CONTINUOUSLY CASTING AND REFINING A METAL IN A BOTTOM-LESS MOLD Louis Babel, Sauvigny-les-Bois, France, assignor to SocieteMetallurgique dlmphy, Paris, France, a company of France Filed Dec. 27,1967, Ser. No. 693,954 Claims priority, application France, Jan. 6,1967,

Int. Cl. B2241 27/02, 11/10 US. Cl. 164250 3 Claims ABSTRACT OF THEDISCLOSURE This invention relates to a process and apparatus forcontinuously casting and refining a metal.

According to the invention, there is provided a process for continuouslycasting and refining a metal comprising the steps of introducing slaginto a cooled, bottomless, casting mould above the metal level,maintaining the slag in liquid form, and changing the slag by theaddition and extraction of slag at a location above the liquid metallevel.

According to the invention, there is also provided apparatus forcontinuously casting and refining a metal, comprising a bottomless mouldin which the metal is to be cast, means for cooling the mould, means forintroducing slag into the mould above the metal level in the mould,means for maintaining the slag in liquid form, and means for changingthe slag in the mould.

Features and advantages of the invention will be apparent from thefollowing description of an embodiment thereof given, by way of example,in conjunction with the accompanying drawings, wherein:

FIG. 1 is a vertical section through apparatus according to theinvention, permitting continuous casting and refining of the metal, and

FIG. 2 is a section on a line II-1T in FIG. 1.

The apparatus shown in the drawings has a mould 1 of copper, cooledinternally by Water circulating in ducts 2. The semi-finished metalproduct 3, obtained by solidification of the metal in the mould, isdrawn downwards by a withdrawal machine, which may be of conventionaltype. The semifinished product includes a portion 4 which is stillliquid and which is supplied by a feed jet 5. This jet, in a knownmanner, is eccentric relative to the product 3.

The installation also includes a duct 6 supplying a stream 7 ofelectrically conductive slag which goes on top of the product 3, forminga layer 8 protecting the metal.

The lower end of a metal mandrel 9, made of copper and cooled by a fluidcoolant such as water circulating in internal ducts 10, dips into thelayer 8 of electrically conductive slag.

3,517,727 Patented June 30, 1970 "ice An axial portion 11 of the mandrelforms a tube for extracting the slag from the layer 8. The slag isexhausted by a device 12, for example a pump or an extraction devicewith an ejector of a known type.

{The mould 1 and tubular mandrel 9 are connected to the terminals of anelectric power supply, for example a single-phase alternating-currentpower supply.

Since the lower end of the-tubular mandrel 9 dips into the slag layer 8,the slag is kept in the liquid state by heating due to the Joule effect,the electric current passing between the mandrel 9 and mould '1.

The molten metal arriving in the form of a jet 5 traverses the slaglayer 8 and flows, by gravity, to feed the liquid portion which is toform the semi-finished product by solidification. The slag is selectedso that while the metal passes through it, the metal is subjected to thehigh degree of refining which reduces the contents of gas and certainother impurities such as sulphur, and which eliminates non-metallicinclusions.

The slag retains its effectiveness because it is continuously replaced,since the duct 6 supplies it above the semi-finished product formed andsince it is continuously extracted by exhausting along the mandrel 9.The layer of electrically conductive slag must be thick enough to allowcorrect refining of the metal traversing it. A suitable thickness may,for example, be of the order of 100 mm. for a mould whose largestdimension is of the order of 200 mm.

The composition of the slag depends of course the refining required andthe grade of steel cast.

It should be noted that the process improves not only the purity andquality of the steels or alloys cast, but also the quality of thecasting skin.

What is claimed is:

1. Apparatus for continuously casting and refining a metal, comprising abottomless mould in which the metal is to be cast, means for cooling themould, means for introducing slag into the mould above the metal levelin the-mould, means for maintaining the slag in liquid form, and meansfor changing the slag in the mould including a tubular mandrel fordipping into the slag and defining a duct for the passage of slagtherethrough, and an extraction device connected to said duct to removeslag from the mould.

2. Apparatus as claimed in claim 1, wherein the means for maintainingthe slag in liquid form includes a heating device.

3. Apparatus as claimed in claim 1, wherein the heating device comprisesan electrical circuit connected to the tubular mandrel and to the mould,the slag being electrically conductive.

References Cited UNITED STATES PATENTS 3,411,566 11/1968 Astrou et al.164281 2,369,233 2/1945 Hopkins 164-52 2,375,107 5/1945 Hopkins 164-82 X3,234,608 2/1966 Peras 164-52 3,344,839 10/ 1967 Sunnen 164-52 J.SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant ExaminerUS. Cl. X.R.

